The present invention relates to a belt-type compression molding apparatus for compression molding a tobacco stream inside a cigarette manufacturing machine into a predetermined shape, the compression molded tobacco stream being delivered from the compression molding apparatus to a wrapping section of the cigarette manufacturing machine.
A cigarette manufacturing machine has an endless tobacco band for sucking a layer of shredded tobacco thereon to form a tobacco stream, and a wrapping section for continuously wrapping the tobacco stream in wrapping paper. A compression molding apparatus used in this type of cigarette manufacturing machine is arranged between the tobacco band and the wrapping section and includes a shoe and a tongue. The shoe and the tongue define a compression molding passage connecting between the tobacco band and the wrapping section. The shoe is located adjacently to the tobacco band and peels the tobacco stream from. the tobacco band to be introduced into the compression molding passage. As the tobacco stream passes through the compression molding passage, the tongue compresses, with its lower surface, the tobacco stream from above, thereby molding the tobacco stream into a predetermined shape corresponding to the shape of the lower surface thereof. This process of compressing and molding the tobacco stream is important in order to ensure smooth wrapping of the tobacco stream in the wrapping paper in the subsequent wrapping section as well as stable formation of a tobacco rod.
The shoe and the tongue are both fixed members. Accordingly, when the tobacco stream passes through the compression molding passage, the shoe and the tongue constitute large resistance to smooth passage of the tobacco stream. Such resistance increases with increase in the speed of the tobacco stream and possibly causes fragmentation of the shredded tobacco in the tobacco stream. Also, as the resistance increases, the temperature of the shoe and the tongue rises due to frictional heat, with the result that the tobacco stream is overheated.
The tobacco rod has the shredded tobacco filled therein, and if the shredded tobacco is shattered or fragmented as mentioned above, a hard spot where the shredded tobacco is closely filled and a soft spot where the shredded tobacco is loosely filled are produced irregularly along the tobacco rod. Thus, when the tobacco rod is cut to cigarette rods of predetermined length in a cutting section of the cigarette manufacturing machine, a soft spot may be situated at the cut end of a cigarette rod. If this occurs, since the filling density of the shredded tobacco is low at the cut end, the shredded tobacco in the cigarette rod is liable to drop from the cut end.
Also, overheating of the tobacco stream results in heat deterioration of the shredded tobacco, spoiling the original taste and flavor of the shredded tobacco.
An object of the present invention is therefore to provide a belt-type compression molding apparatus for a tobacco stream which can prevent the shredded tobacco in the tobacco stream from being fragmented or overheated and yet permits increase in the speed of the tobacco stream, thereby improving the productivity of the tobacco rod.
The above object is achieved by the present invention, and a belt-type compression molding apparatus according to the present invention comprises a compression belt which is formed by part of an extension of a tobacco band, the compression belt defining a compression molding passage for a tobacco stream on one side thereof. The compression molding apparatus further comprises a guide support for supporting the opposite side of the compression belt over an entire area of the compression molding passage, and the guide support includes a guide groove. The guide groove guides travel of the compression belt and also causes the compression belt to be curved in a manner such that the cross-sectional form of the compression belt gradually changes from a flat shape at an inlet of the compression molding passage to an arcuate shape at an outlet of the same.
In the above compression molding apparatus, the tobacco stream is formed by being drawn onto the tobacco band by suction, and as the tobacco band travels, the tobacco stream is conveyed toward a wrapping section of a cigarette manufacturing machine. After reaching the compression band, the tobacco stream is then conveyed along with the running of the compression band. As the compression band advances from the inlet toward the outlet of the compression molding passage, the compression band is gradually curved by the guide groove of the guide support such that the cross-sectional form thereof changes from a flat shape to an arcuate shape. Consequently, the tobacco stream introduced into the compression molding passage together with the compression band is molded into a predetermined shape while being compressed by the compression band. Since the compression band travels with the tobacco stream, it never constitutes resistance to the conveyance of the tobacco stream. Accordingly, even if the speed of conveyance of the tobacco stream is increased, overheating or fragmentation of the shredded tobacco in the tobacco stream can be significantly reduced, making it possible to manufacture high-quality cigarettes or filter cigarettes and also improving the productivity.
Specifically, the compression molding apparatus may further include a compression pulley associated with the compression belt. The compression pulley defines the terminal end of the compression belt and has an annular groove on an outer peripheral surface thereof for receiving the compression belt in an arcuately curved state. The extension of the tobacco band has a return portion situated on a downstream side of the compression belt. The return portion is guided by the annular groove of the compression pulley while being kept in a curved state, and after passing the compression pulley, returns to a band roller for the tobacco band. The compression pulley is rotated synchronously with the band roller, and as the compression pulley rotates, the compression belt is pulled from the band roller toward the compression pulley.
As stated above, the compression belt and the tobacco band form a one-piece member, and thus no special member serving only as the compression belt is required. Also, since the compression belt travels synchronously with the tobacco band, the tobacco stream is transferred smoothly from the tobacco band to the compression belt.
The compression molding apparatus may further comprise stabilizing means for stabilizing the travel of the tobacco band and its extension. The stabilizing means includes a tension pulley rotatably arranged between the compression pulley and the band roller, and the tension pulley pushes the return portion of the extension toward the compression pulley and the band roller. The tension pulley serves to apply a predetermined tensile force to the return portion, and at the same time to secure a sufficiently large angle of contact between the return portion and the compression pulley, thus enabling the compression belt to travel smoothly while being pulled by the compression pulley.
In addition to the tension pulley, the stabilizing means may further include a tension roller. The tension roller is arranged near the band roller on one side thereof opposite the compression pulley and is supported rotatably. Like the tension pulley, the tension roller serves to apply a predetermined tensile force to the tobacco band and also to secure a sufficiently large angle of contact between the tobacco band and the band roller. Consequently, the tobacco band can be pulled reliably by the band roller, whereby the travel of the tobacco band is stabilized.
The compression molding apparatus may further include flattening means for flattening the extension, that is, the return portion of the tobacco band. The flattening means reshapes the return portion, which is curved as it passes the compression pulley, into a flat state before the return portion reaches the band roller.
Specifically, the flattening means includes the tension pulley rotatably arranged between the compression pulley and the band roller, and the tension pulley has a flat outer peripheral surface pressed against the return portion. The tension pulley applies a predetermined tensile force to the return portion and at the same time reshapes, with its outer peripheral surface, the curved return portion into a flat state. Consequently, the return portion, that is, the tobacco band, can be brought into close contact with the band roller, whereby the travel of the tobacco band is stabilized.
The flattening means may further include a flattening guide, in addition to the tension pulley. The flattening guide is a fixed member arranged between the tension pulley and the band roller. After passing the tension pulley, the return portion comes into sliding contact with the flattening guide, and this sliding contact prevents the return portion from becoming curved again from the flat state.
The compression molding apparatus may further include a molding guide contiguous with the compression pulley on an immediately downstream side thereof in the direction of conveyance of the tobacco stream, and the molding guide defines an extended portion of the compression molding passage.
Specifically, the molding guide includes a guide groove extending from the compression pulley and having an arcuate cross-sectional form. The arc of the guide groove at one end thereof contiguous with the compression pulley has a radius of curvature equal to that of the annular groove of the compression pulley. Consequently, the tobacco stream is smoothly introduced into the guide groove of the molding guide after passing through the compression molding passage.
Further, the molding guide has a scraper edge at one end thereof contiguous with the compression pulley. The scraper edge peels the tobacco stream from the terminal end of the compression belt, thus permitting the tobacco stream to be introduced into the guide groove of the molding guide without fail.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.